The flow adjusting valve is an important component of the refrigeration system, and is another one of four fundamental components of the refrigeration system besides the evaporator, the compressor and the condenser. Operation process of the flow adjusting valve is generally as follows: with the energizing or de-energizing of the coil device, the valve needle is driven to adjust the opening degree of the valve port, so as to adjust the flow of the refrigerant.
In general, a different flow curve should be set for the flow adjusting valve according to different application environment. Referring to FIG. 1, FIG. 1 is a flow curve schematic diagram of a flow adjusting valve in the prior art.
As is shown in FIG. 1, the longitudinal coordinates V represents the flow of the refrigerant flowing through the valve port of the flow adjusting valve, and the horizontal coordinates S represents the distance between the valve rod of the flow adjusting valve and the valve port. As is shown in FIG. 1, as the valve rod is gradually moved away from the valve port, the flow of the refrigerant is gradually increased, forming a flow curve having a certain curvature.
In the prior art, in order to form the flow curve as shown in FIG. 1, U.S. Pat. No. 6,568,656B1 discloses a flow adjusting valve. Referring to FIG. 2 and FIG. 3, FIG. 2 is a structural schematic view of a flow adjusting valve in the prior art; and FIG. 3 is a pressure distribution schematic view of the refrigerant at the valve port of the flow adjusting valve shown in FIG. 2.
As is shown in FIG. 2, the flow adjusting valve in the prior art includes a valve seat 1′ and a valve rod 2′. The valve seat 1′ is provided, in the valve cavity thereof, with a valve port 1′1, and the valve rod 2′ is moved up and down along the axial direction, thereby adjusting the flow of the valve port 1′1. As is shown in FIG. 2, the valve rod 2′ has a split structure and includes a conical tube segment 2′1, a cylindrical tube segment 2′2, and a sealing member 2′3 provided between the conical tube segment and the cylindrical tube segment. As the valve rod 2′ is moved up and down, the valve port 1′1 is opened or closed by the sealing member 2′3. Furthermore, the valve rod 2′ is provided with a balancing flow passage 2′4 for communicating an upper end and a lower end of the valve rod 2′, thereby balancing the effect of the pressure exerted by the refrigerant on the valve rod 2′.
As is shown in FIG. 2, since the lower end portion of the valve rod 2′ is provided with a conical tube segment 2′1, as the conical tube segment 2′1 is away from the valve port 1′1, the flow curve shown in FIG. 1 can be formed. Meanwhile, the curvature of the flow curve may be adjusted by changing the conical degree of the conical tube segment 2′1. However, the flow adjusting valve has disadvantages as follows.
Firstly, as is shown in FIG. 3, since the lower end portion of the valve rod 2′ is provided with a conical tube segment 2′1, pressures from the refrigerant at the valve port 1′1 are substantially divided into three grades, that is, pressure grade A which has the maximum pressure (at the densest position of the transverse schematic line), pressure grade B which has the moderate pressure (at the denser position of the transverse schematic line), and pressure grade C which has the minimum pressure (at the sparsest position of the transverse schematic line). Therefore different positions of the conical tube segment 2′1 are subject to the above three different pressures, respectively. As shown in FIG. 3, the lower end opening of the balancing flow passage 2′4 is extended in the area of the pressure grade A, thus the upper end of the valve rod 2′ suffers a pressure of pressure grade A. It can be seen that, under the precondition that the force bearing areas of the upper end and lower end of the valve rod 2′ are the same, the force suffered by the upper end of the valve rod 2′ is different from the force suffered by the lower end (i.e., the conical tube segment 2′1) of the valve rod 2′. That is, pressures exerted by the refrigerant on the valve rod 2′ are uneven. Therefore the stability of the axial movement of the valve rod 2′ is affected.
Secondly, as is shown in FIG. 2, during the closing of the valve port 1′1 by the sealing member 2′3, the sealing member 2′3 may collide with the valve port 1′1. Since the impact force is large, after performing the opening and closing operations time and again, the sealing member 2′3 is easy to be deformed, resulting in the leakage of the refrigerant and a short service life of the sealing member.
Thirdly, as is shown in FIG. 2, the valve rod 2′ has a split structure and includes a conical tube segment 2′1, a sealing member 2′3, and a cylindrical tube segment 2′2, and the three components are connected in a threaded manner or in other connection manners. The valve rod 2′ has a risk of being loosen and disconnected due to the bump and vibration in transportation or the vibration of the compressor in operation.
In addition, it should be noted that, in the prior art, a flow adjusting valve disclosed in Chinese Patent Application No. 200580023202.7 also has the above three disadvantages, reference may be made to the specification of the application, which will not be described in detail herein.
In view of this, it becomes an urgent problem to be solved by the person skilled in the art to improve the flow adjusting valve in the prior art, such that, on the one hand, different flow curves that are required can be obtained based on the different application environments, and on the other hand, pressures exerted by the refrigerant on the valve rod along the axial direction thereof can be balanced.